Does the "ban" say this:
Sorry Guest, you are banned from using this forum!
Go away, RIPEnet.
If so, try again with a different browser. That "ban" notice started happening a while back. For a while I was getting it on Chrome but not Firefox, so I was using Firefox for the forum and getting in just fine. Then the "ban" appeared on Firefox but wasn't on Chrome, so currently I use Chrome to access the forum. And so on.